PROGRAM f07vufe ! F07VUF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. Use Statements .. USE nag_library, ONLY : nag_wp, x02ajf, ztbcon ! .. Implicit None Statement .. IMPLICIT NONE ! .. Parameters .. INTEGER, PARAMETER :: nin = 5, nout = 6 CHARACTER (1), PARAMETER :: diag = 'N', norm = '1' ! .. Local Scalars .. REAL (KIND=nag_wp) :: rcond INTEGER :: i, info, j, kd, ldab, n CHARACTER (1) :: uplo ! .. Local Arrays .. COMPLEX (KIND=nag_wp), ALLOCATABLE :: ab(:,:), work(:) REAL (KIND=nag_wp), ALLOCATABLE :: rwork(:) ! .. Intrinsic Functions .. INTRINSIC max, min ! .. Executable Statements .. WRITE (nout,*) 'F07VUF Example Program Results' ! Skip heading in data file READ (nin,*) READ (nin,*) n, kd ldab = kd + 1 ALLOCATE (ab(ldab,n),work(2*n),rwork(n)) ! Read A from data file READ (nin,*) uplo IF (uplo=='U') THEN DO i = 1, n READ (nin,*) (ab(kd+1+i-j,j),j=i,min(n,i+kd)) END DO ELSE IF (uplo=='L') THEN DO i = 1, n READ (nin,*) (ab(1+i-j,j),j=max(1,i-kd),i) END DO END IF ! Estimate condition number ! The NAG name equivalent of ztbcon is f07vuf CALL ztbcon(norm,uplo,diag,n,kd,ab,ldab,rcond,work,rwork,info) WRITE (nout,*) IF (rcond>=x02ajf()) THEN WRITE (nout,99999) 'Estimate of condition number =', & 1.0E0_nag_wp/rcond ELSE WRITE (nout,*) 'A is singular to working precision' END IF 99999 FORMAT (1X,A,1P,E10.2) END PROGRAM f07vufe